Abstract: Refraining from the use of force is specified in Item 4，Article 2 of The Charter of the United Nations and is also a rule of jus cogens. Although The Charter of the United Nations does not define“the use of force”，the word “force”should be restricted to the military category according to the rules that are used to interpret treaties. As a document intended to regulate international cyber security，however，the Tallinn Manual qualifies cyber-attacks as“use of force” . The Manual is neither legally binding nor is a legal creation；the qualification of the use of force in the Manual is both defective in theory and misleading in practice. The Tallinn Manual’ s definition needs to be responded to and reconsidered by traditional rules of the international law.